The field of the invention relates to waste pulping equipment for waste treatment and disposal.
In equipment of this type, waste materials are introduced into an impeller-created vortex of water, reduced to a pulp, and passed on to a water extraction device with the excess water separated and returned to the pulper for reuse. Such waste pulping machines are often provided with blades or cutting members mounted to the impeller to provide a shearing action as the impeller rotates. The blades also enable the pulping equipment to handle a quantity of non-pulpable material, such as plastic, which generally constitutes a minor portion of the waste to be disposed.
When introducing waste material into the tank of a pulping machine, such potentially damaging materials as silverware or bottle caps could damage the impeller. Horizontally disposed impellers are inherently subject to such damage. Vertically disposed impellers are not, but vibration problems have limited their utility. This is due to cavitation, i.e., the formation of air pockets in the slurry chamber. Providing a water level which is higher than the level of the impeller has been suggested as a solution in commonly assigned Ser. No. 714,609 filed Aug. 16, 1976, now abandoned, but efficiency of the apparatus is reduced to an extent. Another problem with this method is that floatables such as styrofoam will not be pulped due to their flotation above the impeller.
Another desirable feature of pulpers is to maximize the throughput of water and waste from the pulper to the extractor. Due to the fact that the rotating slurry within the pulper has inertia, simply attaching a discharge pipe to the walls of the slurry chamber does not provide for optimal throughput.